Built-up wood panel



Dec. 8, 1953 Filed Sept. 18, 1948 F. WEYERHAEUSER 2,661,511

BUILT-UP WOOD PANEL 2 Sheets-Sheet 2 structures illustrative of the shown:

Patented ec. 1.953

BUILT-UP WOOD PANEL Frederick Weyerhaeuser, St. Paul, Minn., as-

signor, by mesne assignments, to Rock Island Millwork Company, Rock Island, Ill., a corporation of Illinois Application September 18, 1948, Serial No. 49,911

2 Claims. (Cl. 20-91) This invention relates to improvements in wood panels.

In. the manufacture of wood panels from boards, kerng of the boards longitudinally or grain-wise has been proposed heretofore in an effort to avoid excessive, uncontrolled expansion, and warpage of the panel under circumstances producing unbalanced surface conditions. For sone purposes, as where the boards are concealed in use, kerng on one or both sides is'not objectionable, except for the structural weakening of the boards. that results from the kerng, as a result of which weakening, conventional nailing of the boards to a supporting framework, as to studding or joints, retains the kerfed boards in position generally against the forces that tend to warp or cause them to change dimensionally. Merely kerng a surface of a board does not in itself effect stabilization of the board, that is, kerng alone does not prevent cross-grain expansion and contraction, nor prevent that warpage or cupping resulting from unbalanced moisture conditions within, or affecting unequally the faces of the board.

It is an object of the present invention 'to provide an improved panel made of one or more boards that is substantially stabilized and that may be provided with one or with both faces that are uninterrupted or continuous and thus subject to conventional decorating or finishing Where desired for use in exposed positions.

Another object Vof the invention is to provide a panel structure that, while kerfed grainwise, is sufliciently rigidiiied crosswise as to make possible the manufacture of panels of substantial width without danger of breakage during subsequent handlings.

In the accompanying drawings wherein panel invention are Fig. 1 is a perspective View of a panel formed of boards assembled to provide one continuous decoratable surface or face.

Fig. 2 is an enlarged broken end elevation o the panel shown in Fig. 1.

Fig. 3 is a broken perspective view of a composite panel formed by securing together, back to back, two panels of the type shown in Fig. 1.

Fig. 4 is a broken perspective view of a modication of the panel shown in Fig. 3.

Fig. 5 is a broken side elevation of the panel shown in Fig. 4. A

Fig. 6 is an end view of the panels shown in Figs. 3 and 4.

The panel structure shown in Fig. 1 is formed of boards l0 glued together edge-wise with butt joints as indicated at l1. The glued edges'may' be matched if desired. The boards employed in forming the panel may be of equal or of random widths and may be of different lengths if desired. Where boards of length less than the length of the panel are utilized, the end joints Ila may be glued matched or butt end joints, the former being preferred. Hence, in accordance with the present disclosures, boards that would be considered in some wood-working plants as unsuitable for building up panels may well be utilized in the manufacture of panels embodying the present improvements.

The boards I0 are kerfed on one side, which side usually will constitute the rear face or back of a nished single panel. Hence, in the kerng of the boards, consideration may well be given to surface conditions such as grain, knots, etc. of individual boards where the completed panel is to be employed in locations where the front face will be exposed and decorated to provide a wall or like surface. When the panels are to be employed for structural purposes only, as for sheathing, suboors or the like, little or no attention need be given to the selection of board faces prior to kerng operations.

The illustrative panel shown in Figs. 1 and 2` is provided with kerfs I2 that extend longitudinally, that is, lengthwise or substantially grainwise of the individual boards, and are suitably spaced apart and are of appropriate depth relative to the thickness of the panel. If the panel shown in said figures is assumed to be approximately 1/2 inch thick, the kerfs l2 may be 1% inch in depth and in width about %i inch. A spacing 3A inch between kerfs has been found satis-` factory in panels of the thickness mentioned.

The forward face I3 of the panel is unkerfed and is in factthe outer face of a continuous portion of the panel disposed outwardly of the plane determined by the bottoms of the kerfs l2. This continuous portion is designated I 4 and is approximately 1/8 inch in thickness in the panel of the specifications given above.

Extending transversely of the panel formed byv the boards l is a plurality of grooves or channels I6 for receiving splines l1. The channels I B'are shown of the same depth as the kerfs and should not be of less depth although they may be somewhat deeper to provide continuous bottom surfaces on which the lower edges of surfaces of the splines can seat to insure close contact for the glue joints between the splines l1 and the bottoms of said spline-grooves IB. The splines shown in Figs. l and 2j may be 1A inch Wide and are shown of a thickness such that their outer edges lie flush with the rear face |311. of the panel. The size of the splines however, may be varied as required, the dimensions of the same and of the panel, and the kerfs being that employed in a practical panel structure using commercially available wood, such as pine, for example. The splines are formed of any suitable material which is 'lengthwise stable, that is, not subject to appreciable lengthwise expansion or contraction. Where the splines are made of Wood, the grain of the splines extends lengthwise and hence the splines do not varyinlegth with varying conditions of humidity, being formed of known woods having"r`i"'appreciable expansion or contraction lengthwise-byfrealson of variations in moisture content. s

A panel structure such as is shown in l may be manufactured in substantial `widtlisfffor example, two or two and one half feet onmore and of such length as is conventional commer'- cially, for example, eight feet. However, the invention permitsI of any length and'o'flany width. The number of splines employed is sil'chias ifo r'i'gidify the panel transversely notonl'y to -prei vent breakage'lengthwise during handling but to vstabi'lize'the panel against warpage or cuppingl and' dimensional change crosswise of the "wood by reason'of variations in-lnoisture content of the wood, or bythe treatmentas by painting, *of the continuous outer decoratableface' ll `As described above, the kening extends beyond the median^plane of the'panel, leaving only a relatively thin continuous board portion I d llying between the -forward face I3 oi the' panel'V and the'parallel planeipass'ing throughthe vbottoms I of -the'illustrated kerfsiZi This-portion-oi the boardv is not stabilized by reason of the'kerfs and expansion or contractio'n'ther'eof tends 'to-vary the total Vwidth'iof thepanelI-Iowever, `duetto' the fa'ct that the portion |4` is relatively thinfthe` expansive and -contractive iorcesexerted thereby due 'to' changes in moisture'contentfo thetend# ency of --said portion 'to -warpY from iitsl*originall plane, are-controllable bythe splines |'4|I which arev sufficient-in number to stabilize the panel under normal conditions'of storage aiidfnsef In' the drawing, six Lsplines are-shown spaced 'lone gitudinallyalong thepanel. E {pvveverfaigreater number of` splines may be employed'ii desired,l or splines of greater width or of material' afford' greater resistance to warpage or 'dimensionalialf i terations may be'4 employed? For "ordinar'yf corn' mercialpurposesY however, the panel'j-"as-'above described, is satisfactory since'it vis ldesigned to be'lsecured, as by nails, to a rigidijyin'g fijarneor" support, such as studding, -`rafters` joists-'orith like structural units that' resist "warpa'jigfe'e-ivefifl"` under extreme' conditions thatlefiect an iinbal'' ance of the Vforces affecting the l*faces 'ofiithe panel, as painting,paperin`g or'o'ther applied to the face |3 thereof.

" The kerfsI |2 subdivide` the board and iorm ofn the rearL-portion I81 of the panellongitudinally disposed' ribs |91?, of which ribs-lateralfr (':s'ro'ssI` wise expansion is accommodated by' the adjace'rit'u kerfswithout alecting the overiall widthjofv the panel.l The strips I9 stilen-thepanel lagainst ltransverselexure or'warpage along a transverse axis', while the splines-stabilizettheforwardpo# tion I4 ragainst crosswise dimensional alteratipn' and sti'ilenthe panelas a whole 'against longi- Where a more completely and permanently l and-spl`il`les 23, while the latter panel 2| has similar kerfs 24 and splines 25. It will be seen iiiirjig 3ftliai`tli'esplines 23 and 25 of the two mating panels, 2Q and 2|, are not in registration,

but rathelwalternate in a lengthwise direction of the panel. Such arrangement is not essential sincefthesplinesi'xny be arranged in registration; desired, or splines common to the two mating panels may be employed as shown at 26 in Figs. and 5. In this' respect only, the panel o'f Fig. 4 "diners frbin'ihstriictiii'e sho' in Eig. 3 and hence a description of ,the latter will' suice asa description oftheforrner except' er the diterencejust mentioned.

'The mating panel s"'| and" 2|, are securedtogeilier as iiyg-1uingV along their kerfed faces; Whig' 1 are' the iea'r'fa'ce's oi the p anelspon'sideddn i'` vidually, andwhich faces' "constitute" 'affgll'le on Vplane 2,1 in' the 'compositi v"pa'nelf splines 2 common'totl'ietwo panels" are ployed, as siiovvniri Fig/,trief spl AS 2.6. ma' glued in the registering channls tl'i'etwn ing panels conveniently with the assemblyof two panels 2li and 2|, 0i thesblies iiijayl glued in ihecliaiinels of one of 'the baiiels'iiii; iidii the channels of the second 'panel Lat t ti if assembly" and the gluing* 'igeihe'f of" ifi panels, or, if desiredfsiorne ofthe eonlnionsplinesjv may be glueiriiiiwsomebf ineen 'ls'bfoi' panel and ilie remaining" splines; y channels of the second 'panel'prlorto as'sm the other y, of the two'pan'els'f Suitable p" ess is'enployd in the assembly'operation".VWM A After a composite panel has been removed from thepressfthe'cornposite 'stricture vii'lfl'e found to have -rernarl;aliil"stallility'"capableI MT resisting effectively" the faites tliatnriiili'y 62? v'arpageu 'and dimensional variatie4 's1 treinsv' ly'o'f w'oad Danels'ofsinlil'ar size." ASuch' cornpoSl l panelsmay' iliefefiebe 'iis'eiinot nly" as, or strlicifu'resr whichare' parts vof'builli'rlgfs ashin sheathing; sub-'iisigoi thelikfii'vhicl iits by reisen 'of ilieii' sizei'fediie'th'i'imid lbr" involved'V the erctien Vf's'uch structures? 'Iv. may 2111's@l be employdas exposdmelements'I in. al structures 'and' be finished, "tl'ia't'f is "stained, `va nished, enamelled! painted or paprdpn lone surface olf on both surfaces 'Wher'dsir'df" The stability of the composite parl'swprovided bythe construetion disclosed is such that theirran'ge 'f'y usefulness is lnot lilnit'edmtlo locatins afb'mg a rigid backing or support in resisting K for" transverse dinjlen sionalchange.` 'v

AS Shown in Figs 3 t0.6.,f.h;e cqmriositeaangl.. has two relatively tlirl- Continuous politicns and 29, constituting the outer facesV of ,the panelLv andeach corresponding to` the'portio'n t4; 'of Fi'g.' 1:' The facia-Fportions"28;29;"'are' integral, in the form lshovlfn"i'rrFigf'I Vwith the respectivev longitudinalT ribs 3 v'and 3| in'to" Whi'cli ribs"the remainder of each mating panel isffebtdif viiied bythepaiallel krn'g;-=-rlie relatively thier portioI ','theYiibs/ contraction of the panel as a whole since the spaces provided by the adjacent kerfs effectively accommodate the expansion of the individual ribs. Hence the splines actually are required only to resist the expansive and contractive forces exerted by the thin continuous facial portions 28, 29, and the number and size of the splines employed is at least adequate for that purpose.

The expansion of the ribs 3E! or 3|, which are the relatively thick portions between kerfs of each single panel tends to cup or deform the exterior surface portions 28 and 29. However, the rear faces of the ribs of each single panel are glued to similar faces of the mating panel, whereby the tendency of any rib to expand or contract transversely is resisted, and in fact neutralized, by the attached rib or ribs, especially where the kerfs are staggered as shown in Figs. 3, 4 and 6. For example, tendency of any one of the ribs l to expand or contract, as the strip designated A, Fig. 6, is accommodated by the adjacent kerfs 22, but since rib A is glued to the opposing half portions of ribs B and C of the mating panel (which ribs B and C wnl normally have a like tendency to expand or contract under any condition tending to cause transverse dimensional variation of rib A) movement of the left hand portion of rib A to the left due to expansion or contraction will be opposed by a similar tendency of the right hand portion of rib B to move to the right. Likewise movement to the right of the right hand portion of rib A will be opposed by the tendency of the left hand portion of rib C to move to the left. Hence the staggered relation of the kerfs, providing the described overlapping relation of the ribs, provides neutralizing resistances to lateral expansion or contraction of the internal portion of the composite structure that would otherwise tend to distort the panel or alter its crosswise dimension or tend to produce cupping in the outer faces 28, 29. The staggered relation of the kerfs rather than a registering relation as between kerfs of the mating panels, is preferred also for the reason that a structurally stronger composite panel is thereby provided. As will be apparent in Fig. 6 the original opening of each kerf in one mating panel is backed by a solid thick rib of the other mating panel. Thus, the weakening of the original board by the kerfing operation, is overcome by a compensating reinforcement effected by securing a relatively thick rib 39 or 3| as a closure for each kerf. Likelihood of longitudinal splitting of the plane panel face along a kerf therefore is materially reduced by the described staggered relation of the kerfs. Hence, assemblage of the mating panels with the kerfs in registration is not preferred.

While the mating panels are shown and described as being formed of boards of such thicknesses that kerng thereof to provide the integral thin facial layers 28 and 29, and strips 30 and 3|, is practicable by known woodworking equipment, it is within the contemplation of the invention that the ribs need not be integral with the facial layers in the limited sense described, but that the ribs may be separate strips integrated with thin layers by being glued to the latter in spaced parallel relation to provide spaces corresponding to the described kerfs, and that such glued-up panel, after being provided with splines as above described, may be employed similarly to the structure shown in Fig. 1, or may be assembled in pairs to provide composite panels of the general character described.

Other modifications of the illustrative structure utilizing the principle of the present disclosure may be employed without departing from the spirit of the invention dened by the following claims.

I claim:

l. A two-layer structure comprising two panels adhesively united facewise to each other, each panel comprising a plurality of boards of uniform thickness placed edge to edge in panel formation with the grain of all the boards extending parallel to the resulting edge-joints of the panel, the resulting assembly having one face uninterrupted and the other face provided with a multiplicity of kerfs all having uniform depths which are a major portion of the thickness of the assembly, the kerfed face having spaced parallel rectangular cross-sectional channels cut therein to the same depth as the kerfs and extending at right angles to the kerfs, and lengthwise-stable splines filling said channels and adhesively secured to the bottoms thereof, the said two panels in being adhesively united at their kerfed faces having each kerf opposed by unkerfed wood in the opposite panel.

2. A two-layer structure comprising two panels adhesively united facewise to each other, each panel comprising a plurality of boards of uniform thickness placed edge to edge in panel formation with the grain of all the boards extending parallel to the resulting edge-joints of the panel, the resulting assembly having one face uninterrupted and the other face provided with a multiplicity of kerfs all having uniform depths which are a major portion of the thickness of the assembly, the kerfed face having spaced parallel rectangular cross-sectional channels cut therein to the same depth as the kerfs and extending at right angles to the kerfs, the said two panels in being adhesively united at their kerfed faces having each kerf opposed by unkerfed wood in the opposite panel, and also having their channels in register, and a common lengthwise-stable spline in each pair of registering channels adhesively secured to the bottoms of the registering channels.

FREDERICK WEYERHAEUSER.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,718,585 Roos June 25, 1929 1,777,190 Winkler Sept. 30, 1930 FOREIGN PATENTS Number Country Date 4,074 Great Britain l Mar. 25, 1899 379,170 Great Britain Aug. 25, 1932 34,393 Netherlands Aug. 15, 1934 434,053 Great Britain Aug. 26, 1935 

